The Other Two-in-One Hero
by SeaSpectre160
Summary: The Flash (2014)/Kamen Rider W: On their way to Philadelphia, Ronnie and Prof. Stein meet an odd pair who understand what it's like to be two people in one. After Flash S1E14 'Fallout' and post-series for KRW. No pairings. Rated T to be safe, for language.


**Okay, for anyone who only clicked this link because they just know one of the shows:**

 **The newest Flash TV series features two recurring characters named Ronnie Raymond and Prof. Martin Stein. When a huge Particle Accelerator explodes, it gives several people in the fictional Central City superpowers, including the man who becomes the superhero Flash and these two. Since the explosion basically threw Ronnie into Prof. Stein, they gain the ability to fuse into one entity called Firestorm. At first their joined body becomes more unstable and threatens to go nuclear, but the main characters, including Ronnie's fiancée Caitlin, manage to stabilise them. But the Army is still interested in capturing them and studying their powers in order to duplicate them, so the pair, now able to separate and merge at will, go on the run.**

 **Kamen Rider W follows Shōtarō, a young private detective, and his partner Philip as they fight monsters called Dopants as the Two-in-One Kamen Rider W. Philip has special powers that he gained at the age of five, and since then, an evil organisation called the Museum has been using him to create the devices that turn people into Dopants. Shōtar** **ō and his mentor rescued Philip from them a year prior to the main events of the series, but the mentor was killed while they were escaping. By the end of the series, Philip's entire family (most of whom were leading members of the Museum) has died, but others have continued making those devices, so the adventure continues.**

 **DISCLAIMER: I don't own The Flash or Kamen Rider W or the characters of either show.**

 **WORD COUNT: 2450**

* * *

 _Thursday, March 26_ _th_ _, 2015_

A perfectly ordinary day for the people in Dayton, Ohio was rather suddenly interrupted when the metallic creature started rampaging through the shopping district. Cackling madly, he began shooting fire from the flamethrowers mounted on each arm, aiming at whatever he thought he could burn. Benches, decorative shrubs, people, he didn't discriminate.

A pair of men, one white-haired wearing glasses and one dark-haired in his twenties, dove for cover behind an overturned café table. They held a quick, tense debate before the younger man pulled out an odd black-and-silver device and attached it to his chest. Then the two of them clasped hands, and in a swirl of flames, the older man seemed to disappear while the younger one's body became wreathed in fire.

He stood up and charged the attacking creature, completely disregarding the flames hitting him, and then hauled back and punched him in the face. The fire monster stumbled back, but recovered and concentrated a torrent of flame on his opponent, obviously not yet catching on to the fact that it was having no effect whatsoever. The man followed up with a few more punches and some kicks, this time knocking the monster down. Forced into hand-to-hand combat since his flames were useless, he instead used his long torches as melee weapons to fend the man off long enough to get back up.

Before either combatant made another move, however, a third man came onto the scene. He was dressed head-to-toe in a strange, leathery costume, complete with a helmet. His right side was green with gold accents, his left black with purple, and the middle was a shiny white. The round, bug-like eyes in the helmet were red, and he wore a silver and gold belt with a large buckle shaped like a letter X with wings.

"Found you!" the newcomer cried in moderately accented English, his left eye flashing for some reason, "Dopant!"

"Damn it!" the creature spat, speaking for the first time, "I thought you were ash by now!"

"We're harder to burn than that," the late arrival replied. Strangely, his voice sounded different from when he first spoke, and this time the right eye was flashing along with his words. Without waiting for a reply from the 'Dopant', he leapt forward and began to deliver a flurry of punches and kicks.

The Dopant, being rather on the bulky side, wasn't quick enough to evade or block all the blows, and so retaliated by shooting a close-range burst of flames at his attacker, who stumbled back.

"PRISM BICKER!" A broad-bladed sword with an X-shaped attachment near the handle suddenly appeared, seeming to come out of his chest. He then pulled out an odd device that resembled a USB stick with the letter P written on it and tapped a button on it. A new voice seemed to boom out of nowhere: "PRISM!" He inserted it into the handle and then pulled the sword away from the other part, now resembling a shield. Blocking the flames with his shield, he charged forward and brought the sword down, severing a thick tube running down his enemy's left arm. Transparent, yellow fluid immediately began leaking, filling the air with the smell of accelerant.

Deciding that the man with the two voices was an ally, the burning man attacked the Dopant from behind, lunging for the right arm and the identical fuel line on it. He ripped it out, but apparently forgot that his hand was on fire. The fluid ignited, causing an explosion that launched him and the masked man several yards away.

"Gah!" the man yelled, the left eye flashing again, "Watch it!"

Meanwhile, the Dopant was staggering to his feet, having somehow survived the blast. "Damn you, Kamen Rider!" he swore, aiming both flame throwers at the 'Kamen Rider'. A tiny flame spat out of the left one, probably from a small amount of fuel that somehow hadn't ignited with the rest, but that was it. "Oh, shit."

"Looks like you're out of gas," the burning man observed smugly.

"Time to finish this," the Kamen Rider declared (in his 'left eye voice'). He pulled out four more USB-like objects, in green, red, yellow, and black, before inserting each one into a port on the four points of his shield.

Another voice seemed to boom from an unknown source: "CYCLONE! MAXIMUM DRIVE! HEAT! MAXIMUM DIRVE! LUNA! MAXIMUM DRIVE! JOKER! MAXIMUM DRIVE!"

Four balls of light came from the centre of the shield, each matching the colour of one of the USB sticks (except the black one seemed to be represented by purple) and flew around the blade of the sword, leaving trails of light behind them. With a yell, he brought the sword down on the Dopant, the four balls of light all rearing up and striking him at the same time as the blade.

The Dopant exploded into a fireball, and when the smoke cleared, a skinny man in ripped jeans and a hoodie was there, collapsing to the ground as another one of the devices, this one a deep metallic crimson, broke and landed next to him.

"He'll be fine," the Kamen Rider assured his concerned ally, "We'll just leave him for the police to pick up. He's got some arrest warrants out on him for violent behaviour already."

He started to walk away, but the still-burning man called out to him: "Wait! Who are you?"

The Kamen Rider paused, then turned around. "We are the two-in-one Kamen Rider… Double," he introduced himself dramatically, like someone trying to act cool.

"Two-in-One? What do you mean by that? Is it like…?" He paused for a bit, then, struggling for some reason, reached up and pushed a button on the device on his chest. The flames flared before disappearing altogether, and the elder man from before suddenly reappeared next to him.

"I told you no, Ronald!" he immediately yelled.

"And _I_ told you, it's Ronnie, not Ronald!" was the irritated retort.

The Kamen Rider seemed startled for a second, but quickly got over it and pulled two more memory stick things (green and black) out of his belt buckle. There was a gust of wind, a small unidentified object flew away, and the suit and weapons disappeared, leaving an Asian man wearing a fedora standing – no, a second man was also stepping out from behind him. The first was roughly Ronnie's age, while the second was younger, in his early twenties.

"I guess you could say that our cases are, in fact, similar," the younger one stated.

* * *

Spooked by the sound of approaching sirens, the four men made tracks out of there before the police arrived. Once they felt they were far enough away, they settled at another café to talk.

"So, I'm guessing you're wondering what that monster was, right?" the man with the fedora prompted, opening the conversation once they'd all gotten some much-needed coffee. Ronnie and his older companion nodded seriously.

"That was the Torch Dopant," the youngest began to explain, "A man named Keegan Hayes obtained a device known as a Gaia Memory from a dealer in Boston before coming here. When inserted into the body, a Gaia Memory transforms its user into a sort of super-human with abilities unique to that specific Memory. That is a Dopant."

"Philip here is an expert on Gaia Memories and their abilities. Since a side-effect of becoming a Dopant is gradual mental instability, someone needs to stop them, and the regular police aren't equipped for it. So the two of us and a friend deal with the Dopants in our hometown in Japan."

"Normally, Gaia Memory sales are limited to Fuuto City, but we recently learned that a batch had been brought overseas. Shōtarō and I left our friend to handle Fuuto for now, followed them. We were able to track most of them down on our own, then we got a tip from a fellow Kamen Rider working a case in Boston. He gave us a list of buyers and two unsold Memories; it turns out that the dealers were also involved in his case. That sped our progress up, and Hayes was the last one on the list, so now we can head back home."

Ronnie shook his head. "And I thought Central City was bad. Ever since the Particle Accelerator exploded…" He trailed off when he saw his elder friend shaking his head.

"Don't, Ronald, we barely know these people," he cautioned.

"You're from Central City?" Philip asked, leaning forward in interest, "I've read about the Particle Accelerator. It's strange, everything I know about it suggests that it should have gone off without a hitch. I guess that's how you got your powers?"

The older man got up to leave. "Okay, I don't know who you people are, but I strongly suggest you leave us alone. Come on, Ronald, let's go."

"Someone's chasing you," Shōtarō guessed seriously, eyeing the other pair over steepled fingers, "Aren't they?" Ronnie and the other man froze. "We've been there, too. People have been after Philip here because of what he can do; I've been looking out for him for more than six years now. So we're both familiar with the signs of someone who's being hunted."

Ronnie sighed. "A lot of people were… changed… when the Particle Accelerator blew up. We call these people metahumans. They gained special powers, and Professor Stein and I were also affected. The two of us can fuse into one being, and in that state we can shoot fire blasts, and use them to fly." The small grin on his face suggested that he didn't mind the flying bit too much. His friend, Prof. Stein, didn't interrupt him this time. "The Quantum Splicer keeps us stable, so that we can separate again."

Philip brought the fingers of his right hand up to rest on his chin. "Fascinating. This is a new lookup sensation!"

Shōtarō rolled his eyes in mild annoyance, the kind that comes with dealing a person's eccentricities for a long time and coming to accept them. "At least wait until we get back to the hotel."

"Yes, yes, Shōtarō, I know," Philip replied offhandedly.

"You're a researcher, then?" Stein inquired, sitting back down.

"Yes, it's one of my special abilities. I can access virtually all the knowledge on Earth. I don't _know_ everything; it takes the form of a massive library, one filled with so many books that I'd need a lifespan of a couple hundred years in order to read them all. And I need certain keywords if I'm searching for a particular bit of information."

"No wonder people are after you," Ronnie commented in amazement, "You can easily access information people would kill for."

A slightly haunted look appeared in the boy's eyes, indicating that someone _had_ , in fact, killed for what he knew. "I'm aware of that."

Ronnie ducked his head, clearly realising that he'd brought up a sore topic.

"But how are the two of you able to fuse like us?" Prof. Stein asked, moving the conversation to something else.

Shōtarō pulled an odd, mostly-red device out from an inside pocket of his vest. "This is the Double Driver. Philip's mother created it for him. With it, the two of us can combine to become Kamen Rider Double. This is how we take down Dopants."

"That's impressive," Prof. Stein admired, "Your mother must be quite a brilliant woman." He directed the second comment to Philip.

The young man smiled sadly. "She was," he agreed in a small voice.

"But why you?" Ronnie suddenly asked quietly, "Why does it have to be the two of you that fight them, and not someone else? Two members of the team that deals with metahuman criminals back in Central are part of the police department. Why would she put the responsibility on her own son, and not someone with connections to law enforcement?"

Shōtarō frowned. "The Driver will only work with Philip because of other changes caused by the accident that gave him his powers when he was five. And she _did_ intend for someone else to be the other half of Double, but… he was…"

"He was murdered," Philip picked up, "Saving me. And I wound up in Shōtarō's care. Her second choice is, actually, a superintendent in the Fūto's police department, and she even provided him with a Driver of his own after a Dopant killed his family, but Shōtarō and I had been working together for over a year by then, and we weren't willing to break that partnership up."

"It was my fault the first man was killed," Shōtarō continued, "The company that originally created the Gaia Memories was holding Philip captive and using him to create them. My boss and I were private detectives hired by Philip's mother to get him out, but I screwed up. We could've gotten in and out easily if I hadn't. So Philip and I both have our own sins to atone for. That's why it has to be us."

Ronnie and Prof. Stein were stunned silent. They only had pure chance to blame for what happened to them; these young men had so much trauma and guilt driving them to put their lives on the line.

Prof. Stein and Ronnie accompanied Shōtarō and Philip to the airport the next day. "Good luck in Philadelphia," Shōtarō said, "I hope you find what you're looking for."

"Thank you," Prof. Stein replied honestly, "Good luck dealing with those Dopants back home."

"Thanks, we'll be sure to keep in touch. If either of you need anything, just call us. Kamen Riders always look out for their friends."

The pairs shook hands before parting. As they walked away, avoiding security cameras, Prof. Stein and Ronnie felt a bit better about their situation, knowing that they weren't the only ones who knew what they were going through.

"That was interesting," Philip commented as they made their way to check their luggage.

"Yeah, it was," Shōtarō agreed, "They will probably have some hard times ahead. Hopefully, they'll be able to weather it. A mark of true heroes."

"You're just trying to sound like you're not half-boiled again," Philip snarked.

"Oi!"

THE END

* * *

 **Well, I hope you liked that! I'm sort of proud to have written the first ever Flash/Kamen Rider crossover on this site. After this I'll be finishing the last chapter of another Kamen Rider fic, 'Prodigal', and then I'll be working on a sort-of prequel to this one, a Criminal Minds/Kamen Rider Fourze crossover titled 'The Star-Crazy Cult'.**

 **Also, any Kamen Rider fans who also like Harry Potter, feel free to check out my newest poll, to decide which Hogwarts Houses nine Kamen Rider Gaim characters belong in.**

 **Until then, Spectre out!**


End file.
